During the period of June 2000 - June 2001, we initiated six ICM cultures later found to be in compliance with criteria for US federal funding of research on existing hESC. This application seeks support to develop lines of these cells to validate their culture characteristics and phenotype. Our goal is to determine whether these cell cultures will meet adequate quality controls and behave reproducibly as hESC lines, in order to subsequently be made accessible for the research community. We plan to explore the possibilities for establishing such lines, the specific aims being: 1) To recover the KA 08-09 and 40-43 cells from frozen stocks 2) To characterize and quality assure cell lines from KA 08-09 and 40-43 3) For this we will initiate a program to further optimize our cell culture conditions and cryopreservation methodology.